Debugging: Attach to Process for Console App running inside cmd.exe

Question

How do you "Attach to Process..." for a console application thats running from a CMD window and not launched by F5? The reason I ask is because the application takes command line arguments and I want to have a genuine experience.

I've even attaching to CMD.exe , but no luck, or setting a break-point using Console.ReadKey() with also no luck. I'm kind of at a loss here.

Is this possible?

Answer 1

You have some options:

• Use "Debug -> Command line arguments" option in Visual Studio;
• Use "Debug -> Attach to process" and find your process; it is not cmd.exe, but a process with executable name like "MyProject.exe". You can use Process Explorer or another task manager with "tree view" support to easily find the Process ID - just look for the processes started by your cmd.exe.
• Put Debugger.Break() into your code - when this method is executed, the system will launch a dialog asking you to choose what instance of Visual Studio to use for debugging (you can choose the one with your project already open).

Answer 2

To debug from the command line rather than using the VS GUI maze:

• Launch the Visual Studio Command Prompt

• type vsjitdebugger/? which gives you the command example like :

c:> vsjitdebugger [AppName] [Args] : Launch the specified executable and attach to debugger

• typing tlist or tasklist will give you PIDs for attaching to existing processes. example:

c:> tasklist | find /i "web"

Answer 3

It's possible, sure. Try one of these two:

1. Start the process, then go to Debug->Attach and find the process. You may have to refresh to see it.
2. Add a "Debugger.Break()" statement in the code, if possible; that will break automatically (but be sure to remove it or surround it with preprocessor directives so it doesn't get into production code).

Answer 4

2020 UPDATE: to @VladV answer

Debugger.Break() doesn't work anymore.

Try using Debugger.Launch() instead, also put breakpoints after this line, or VS will start complaining.

Answer 5

As others have said, you can specify the stratup command line arguments from within the project and just start debugging within Visual Studio.

If you still want to attach to the running application, you need to attach the debugger to MyApp.exe (whatever your application is called - the exe that gets compiled to the bin\\debug directory) and not cmd.exe. Attaching to cmd.exe it attaching to the command process, not the process of your application.

Answer 6

Just add an registry entry for your exe's name in "HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows NT\\currentversion\\image file execution options", adding a "debugger" key valued with "vsjitdebugger.exe" under it, you can see a dialog pops up asking you to choose a VS version to debug when the exe starts up.

see MSDN " How to: Launch the Debugger Automatically " for more information.

Answer 7

In the projects settings "Debug" section there's a textbox for "Command line arguments:". When the VS debugger starts the C# program, it'll pass those arguments to the process just as if the program had been started form the command line with those arguments.

The alternative is to use a command line debugger. There are a few options here, but in all honesty they're probably not what you want to use instead of VS unless you're getting into some really hairy debugging scenarios. If you're interested in checking them out, there's a good summary in this SO answer:

• MSIL debuggers - Mdbg, Dbgclr, Cordbg

You can also try the techique of putting a call to System.Diagnostics.Debugger.Break() early in your initialization - if the program is running under a debugger, it'll break, it it's not running under a debugger you should be asked if you want to attach one. You can make the call conditionally depending on a configuration file or environment variable setting so you only get the break if you're really interested in it (somewhat intrusive, but not too bad).

Answer 8

I thought I would find some better solutions here but it seem the one I already have is the best. Debugger.Break() just simply don't work for me at all. But some time ago I found VisualStudioAttacher class on GitHub. Can't find the rep right now, but I'm posting my slightly modified version.

You will use it like this.

class Program {
    static void Main(string[] args) {
        VSAttacher.attachDebugger("SolutionFileContainingThisCode.sln");

        Console.WriteLine("Hello World"); //set a brakepoint here
        //...               
    }

}

This will just attach to currently opened instance of visual studio and it doesn't require you to choose the debugger.

Setup

1. Create new class library project named VSAttacher , or whatever you like.
2. Add reference to VSAttacher project in the project you want to debug.
3. In VSAttacher project, add reference to envdte library
4. Paste following code to VSAttacher project :

code:

using System.IO;
using EnvDTE;
using DTEProcess = EnvDTE.Process;
using System;
using System.Collections.Generic;
using Process = System.Diagnostics.Process;
using System.Linq;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;

namespace AppController {
    #region Classes

    /// <summary>Visual Studio attacher.</summary>
    public static class VSAttacher {

        public static Action<object> log = (o) => Console.WriteLine(o);
    
        //Change following variables depending on your version of visual studio
        //public static string VSProcessName = "WDExpress";
        //public static string VSObjectName = "!WDExpress";
        public static string VSProcessName = "devenv";
        public static string VSObjectName = "!VisualStudio";

        /// <summary>
        /// Tries to attach the program to Visual Studio debugger.
        /// Returns true is the attaching was successful, false is debugger attaching failed.
        /// </summary>
        /// <param name="sln">Solution file containing code to be debugged.</param>
        public static bool attachDebugger(string sln) {
            if (System.Diagnostics.Debugger.IsAttached) return true;
            log("Attaching to Visual Studio debugger...");

            var proc = VSAttacher.GetVisualStudioForSolutions(
                new List<string>() { Path.GetFileName(sln) });
            if (proc != null) VSAttacher.AttachVSToProcess(
                    proc, Process.GetCurrentProcess());
            else { 
                try { System.Diagnostics.Debugger.Launch(); }
                catch (Exception e) { }
            } // try and attach the old fashioned way

            if (System.Diagnostics.Debugger.IsAttached) {
                log(@"The builder was attached successfully. Further messages will displayed in ""Debug"" output of ""Output"" window.");
                return true;
            }
            log("Could not attach to visual studio instance.");
            return false;
        }

        #region Public Methods


        #region Imports
        [DllImport("User32")]
        private static extern int ShowWindow(int hwnd, int nCmdShow);

        /// <summary>Returns a pointer to an implementation of <see cref="IBindCtx"/> (a bind context object). This object stores information about a particular moniker-binding operation.</summary>
        /// <param name="reserved">This parameter is reserved and must be 0.</param>
        /// <param name="ppbc">Address of an <see cref="IBindCtx"/>* pointer variable that receives the interface pointer to the new bind context object. When the function is successful, the caller is responsible for calling Release on the bind context. A NULL value for the bind context indicates that an error occurred.</param>
        /// <returns></returns>
        [DllImport("ole32.dll")]
        public static extern int CreateBindCtx(int reserved, out IBindCtx ppbc);

        /// <summary>Returns a pointer to the <see cref="IRunningObjectTable"/> interface on the local running object table (ROT).</summary>
        /// <param name="reserved">This parameter is reserved and must be 0.</param>
        /// <param name="prot">The address of an IRunningObjectTable* pointer variable that receives the interface pointer to the local ROT. When the function is successful, the caller is responsible for calling Release on the interface pointer. If an error occurs, *pprot is undefined.</param>
        /// <returns>his function can return the standard return values E_UNEXPECTED and S_OK.</returns>
        [DllImport("ole32.dll")]
        public static extern int GetRunningObjectTable(int reserved, out IRunningObjectTable prot);


        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern bool SetForegroundWindow(IntPtr hWnd);
        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern IntPtr SetFocus(IntPtr hWnd);
        #endregion

        public static string GetSolutionForVisualStudio(Process visualStudioProcess) {
            var vsi = getVSInstance(visualStudioProcess.Id);
            try { return vsi?.Solution.FullName;}
            catch (Exception) {} return null;
        }

        public static Process GetAttachedVisualStudio(Process ap) {
            var vsps = getVSProcess();
            foreach (Process vsp in vsps) {
                var vsi = getVSInstance(vsp.Id);
                if (vsi == null) continue;
                try {
                    foreach (Process dp in vsi.Debugger.DebuggedProcesses)
                        if (dp.Id == ap.Id) return dp;
                } catch (Exception) {}
            }
            return null;
        }

        public static void AttachVSToProcess(Process vsp, Process applicationProcess) {
            var vsi = getVSInstance(vsp.Id);
            if (vsi == null) return;
            //Find the process you want the VS instance to attach to...
            DTEProcess tp = vsi.Debugger.LocalProcesses.Cast<DTEProcess>().FirstOrDefault(process => process.ProcessID == applicationProcess.Id);

            //Attach to the process.
            if (tp != null) {
                tp.Attach();

                ShowWindow((int)vsp.MainWindowHandle, 3);
                SetForegroundWindow(vsp.MainWindowHandle);
            } else {
                throw new InvalidOperationException("Visual Studio process cannot find specified application '" + applicationProcess.Id + "'");
            }
        }

        public static Process GetVisualStudioForSolutions(List<string> sns) {
            foreach (string sn in sns) {
                var vsp = GetVSProc(sn);
                if (vsp != null) return vsp;
            }
            return null;
        }


        public static Process GetVSProc(string name) {
            var vsps = getVSProcess(); var e = false;
            foreach (Process vsp in vsps) {
                _DTE vsi = getVSInstance(vsp.Id);
                if (vsi == null) { e = true; continue; }
                try {
                    string sn = Path.GetFileName(vsi.Solution.FullName);
                    if (string.Compare(sn, name, StringComparison.InvariantCultureIgnoreCase)
                        == 0) return vsp;
                } catch (Exception) { e = true; }
            }
            if (!e) log($@"No running Visual Studio process named ""{VSProcessName}"" were found.");
            return null;
        }

        #endregion

        #region Private Methods

        private static IEnumerable<Process> getVSProcess() {
            Process[] ps = Process.GetProcesses();
            //var vsp = ps.Where(p => p.Id == 11576);
            return ps.Where(o => o.ProcessName.Contains(VSProcessName));
        }

        private static _DTE getVSInstance(int processId) {
            IntPtr numFetched = IntPtr.Zero;
            IMoniker[] m = new IMoniker[1];

            GetRunningObjectTable(0, out var rot);
            rot.EnumRunning(out var ms); ms.Reset();

            var rons = new  List<string>();
            while (ms.Next(1, m, numFetched) == 0) {
                IBindCtx ctx;
                CreateBindCtx(0, out ctx);

                m[0].GetDisplayName(ctx, null, out var ron);
                rons.Add(ron);
                rot.GetObject(m[0], out var rov);

                if (rov is _DTE && ron.StartsWith(VSObjectName)) {
                    int currentProcessId = int.Parse(ron.Split(':')[1]);

                    if (currentProcessId == processId) {
                        return (_DTE)rov;
                    }
                }
            }
            log($@"No Visual Studio _DTE object was found with the name ""{VSObjectName}"" that resides in given process (PID:{processId}).");
            log("The processes exposes following objects:");
            foreach (var ron in rons) log(ron);
            return null;
        }

        #endregion
    }

    #endregion
}

If you use express version of visual studio, you should change VSProcessName and VSObjectName (this was tested only with express and community versions).